Assalamu alaykum you can do it 2 ways before the salam or after the salam If he makes the prostration before the salam he makes the salam right after completing the tashahud. If he brings the prostration after the salam It is then obligatory to make the final tashahud and then the salam. zad al mustaqni. http://www.scribd.com/doc/19707573/Zad-al-Mustaqni